ADDITIONAL SYSTEM INFORMATION :
Windows 11
Java 22.0.1
JavaFX 22.0.1

A DESCRIPTION OF THE PROBLEM :
With an editable ComboBox, the user can press "Enter" to commit the new value. However, if there is a default Button in the scene, then that button's on-action handler is invoked before the new value of the ComboBox is committed. This is counterintuitive. When the user fires the default button in, e.g., a form, all input should be up to date.

The source of this issue seems to be that a default button's on-action will be fired when a KEY_PRESSED event (for "Enter") bubbles up to the Scene, but the ComboBox commits its value on a KEY_RELEASED event (for "Enter"). The KEY_PRESSED obviously happens before the KEY_RELEASED, and so the new value is committed too late.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Launch provided test application.
2) Type "Hello" (or anything) into the ComboBox and press the Enter key.
3) Observe the output in the console.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Expected to see the ComboBox's value changed first, and for the new value to be available in the button's on-action handler. The expected console output is below.

ComboBox.onValueChanged: Hello
Button.onAction: Hello
ACTUAL -
The ComboBox's value is still null when queried from the button's on-action, and then the value is updated after. Actual console output is below.

Button.onAction: null
ComboBox.onValueChanged: Hello

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Main extends Application {

  @Override
  public void start(Stage primaryStage) {
    var comboBox = new ComboBox<String>();
    comboBox.setEditable(true);
    comboBox.valueProperty().addListener((obs, ov, nv) -> {
      System.out.printf("ComboBox.onValueChanged: %s%n", nv);
    });

    var defaultButton = new Button("Default button");
    defaultButton.setDefaultButton(true);
    defaultButton.setOnAction(e -> {
      var value = comboBox.getValue();
      System.out.printf("Button.onAction: %s%n", value);
    });

    primaryStage.setScene(new Scene(new VBox(comboBox, defaultButton)));
    primaryStage.show();
  }

  public static void main(String[] args) {
    Application.launch(Main.class, args);
  }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
It's possible to for the new value to be committed earlier by adding a KEY_PRESSED event handler:

comboBox.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
  if (e.getCode() == KeyCode.ENTER) {
    comboBox.commitValue();
  }
});

FREQUENCY : always